Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
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Design of steel and composite bridges Highway bridges Joël Raoul
Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
Main selected features
• General presentation and scope of EC3 and • • • • •
EC4 related to steel and composite bridges Materials Structural analysis Cross-section analysis at ULS and SLS Treatment of instabilities Fatigue
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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
application s
Partie 2
bridges Partie 7.1
pylons
Partie 7.2
chimneys Partie 6
Cranes
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Partie 4.1
Partie 4.2
Silos
tanks
Partie 4.3
Partie 5
Pipelines
piling
Partie 1.1
General rules
Partie 1.7
Plated elements loaded transv.
Partie 1.2
fire
Partie 1.8
joints
Partie 1.3
sheetings
Partie 1.9
Fatigue
Partie 1.4
Stainless steel
Partie 1.10
Brittle fracture
Partie 1.5
Plated elements
Partie 1.11
cables
Partie 1.6
shells
Partie 1.12
generic rules
S500 to S690
Eurocode 3 : steel structures
Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
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EN 1994 : composite steel-concrete structures EN 1994-2 general rules and bridges (self-sufficient)
CONCRETE PART
STEEL PART
EN 1992-2
EN 1993-2
Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
Scope of EN1993-2 All steel bridges (in general with an orthotropic deck) and the steel part of composite bridges
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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
Scope of EN1994-2 Composite bridges
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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
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Girder bridges
Economy : two-girder bridges even for 2X2 lanes due to robustness rules
Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
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Box girders
Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
Composite members
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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
Tension members (tie of bowstring arch)
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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
Composite plates
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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
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Filler beam decks In the transversal direction
In the longitudinal direction
Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
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Materials Concrete : Between C20 and C60 for composite bridges (C 90 for concrete bridges)
Steel : up to S460 for steel and composite bridges (S 500 to S 700 in a separate part 1-12 for steel bridges)
Choice of material : avoid brittle behaviour
Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
HOAN BRIDGE 2000
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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
• An overlooked defect is assumed during execution : e.g. : a = 2.2 mm for tf=80 mm
• It grows acc. to fracture mechanics laws (assuming fatigue is governing the design)
• Up to the critical defect depending on Charpy energy at service temperature
• Over a period depending on the inspection periodicity
NOTE: fabrication rules and quality plan are given in EN 1090 They are assumed to be met when using EN 1993
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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
EN 10025
grade quality
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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
Structural analysis
Elastic
Plastic (buildings, bridges in accidental situations)
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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
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Classes of steel cross-sections Cl.1 Cl.2
Mpl
Cl.3 Mel
Cl.4 1
3
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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
Class of flanges
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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
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Global analysis of composite bridges: two aspects are considered
Cracking of concrete on support Non linear behaviour at mid span Mpl,Rd Mel,Rd
Class 1
Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
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Modular ratio used in a composite section n L n0 . 1 Lt n0
Ea E cm
Value of t0 :
and
t t t 0 creep coefficient given by EC2 :
t0 = 1 day for shrinkage t0 = a mean value in case of concrete cast in several stages SIMPLE CALCULATIONS
L is given by :
Permanent loads shrinkage Imposed deformations
1,1 0,55 1,5
Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
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Plate buckling and shear lag
Effectivep width (plate buckling)
effectives width (shear lag)
Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
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Effectives width of concrete slab (ULS and SLS)
bei min(
be1
b1
b1
Le ; bi ) 8
beff b0
be2
b2
Effectives width of stiffened plates Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
1.2
Shear lag at ULS: 3 alternatives, black one recommended beta (alpha0,x)
( 1.4 x )
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1.2
beta élastique en fonction du raidissage
1
0.8
( 1 x)
Shear lag atelu SLS: ( 1.4 x ) elastic (red line)
0.6
0.4
0.2
0.083056 0 0 01/50
0.2
0.4
0.6 x x
0.8
b0/Le
1 1.
Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
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Composite cross-section verification at ULS (M>0) fck/gc
0,85 fck/gc
compression
PNA
ENA
traction
fy/gM Elastic resistance (for class 1, 2, 3)
fy/gM plastic resistance (for classes 1/2)
NOTE : gM is 1.0 (recommended for resistance formulae)
Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
Verification at SLS • Limitation of stresses for steel and composite bridges – As in EN1992-2 and EN1993-2 (fy in the steel part) • Limitation of crack widths for composite bridges – As in EN1992-2 with tension stiffening (wk=0.3mm in general) – Using a simplified method
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Treatment of instabilities Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
expérimental behaviour
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mechanical model
Aeff
M
equ
=0
V
P
2=-cr
1 1
2
Principle of verification Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
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u = ultimate loading (without instability)/ ULS loading cr = critical loading / ULS loading
u cr
PRd=PRk/gM
f ( ) Test /theory (mechanical model) calibration
PRk Pu
NOTE : gM is 1.1 (recommended for « stability » formulae)
Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
Plate buckling of stiffened plates in EC3
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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
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Fatigue verification in EC3 Calculation of DE,2 under a fatigue loading
P = 480kN
• Influence of the type of influence line • Influence of the type of traffic • Influence of the number of lanes
Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
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partial factor for loading= 1,0
verification
Dc =80 Category of detail
Orthotropic decks : recommended detailing Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
Deck plate thickness in the carriage way in the heavy vehicle lane t ≥ 14 mm for asphalt layer ≥ 70 mm
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© SETRA
Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
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1st bridge entirely designed to EC4 in Avignon 4500 t
© SETRA
Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
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Outstanding composite bridges Max span 144 m: Verrières viaduct (composite box-girder bridge) © SETRA
Max S460 thickness 120 mm: Guarrigue viaduct © SETRA
© SETRA
Surface > 20000 m²: Vézère viaduct
Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012
SOME INNOVATIONS / ECONOMY ISSUES
• • • • • • •
Enormous scientific work Simplicity of calculations Robustness (fatigue + brittle fracture) Full exploitation of the materials (postcritical range) Steels up to S690 Hybrid girders Harmonization of the format and the reliability of all the instability formulae • Treatment of stiffened plates • Design of orthotropic decks
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